1. Field of the Invention
This invention pertains, in general, to vehicle emergency passenger restraint systems, and in particular, to a safety belt system capable of operating in either an acceleration-sensitive, chest-belt mode or an automatic-locking lap belt mode.
2. Description of the Related Art
Most vehicles and all automobiles in this country are, by law, equipped with some form of passenger restraint system for restraining the vehicle's passengers in their seats during emergency conditions, such as a collision.
These restraint systems may take the form of inflatable air bags, but typically comprise one or more safety belts which are secured at one end of the vehicle and pass across the lap or chest of the passenger to be secured at a second end, typically by quick-release means, to restrain the passenger within the seat against forward, lateral and upward movement during the emergency condition.
It is well known in the safety-belt art to provide retractor mechanisms which contain a spring-biased spool for winding one end of the belt thereon for extractive and retractive movement of the belt, primarily as a convenience feature. Where such retractor mechanisms are used, it is typical to provide the mechanism with some means for locking the belt against further extractive movement.
In an automatic-locking ("ALR") mode, the retractor is made to lock up against extractive movement upon the occurrence of an event exterior to the extractor, such as a sequential extraction and slight retraction of the belt, as would occur in the buckling-up procedure, or upon the shuttling of a door within the vehicle. In this mode, the belt encircles a portion of the anatomy of the wearer or a supplemental safety device, such as an infant seat or carrier, and serves to prevent movement of the passenger or seat within the vehicle such as would cause any further extractive movement of the belt, as long as the automatic-locking mode is engaged. This type of retractor operation is desirable in the case of restraining children and infant seats during normal operation of the vehicle wherein their unrestrained movement within the vehicle even during non-emergency conditions is undesirable.
An example of such an automatically-locking retractor mechanism is discussed in U.S. Pat. No. 3,604,654 to R. W. Stoffel. An automatic-locking retractor having selector means for selectively engaging and disengaging the automatic-locking mode is discussed in U.S. Pat. No. 3,771,814 to F. Hahn.
An example of a child safety seat and automatic-locking restraint means therefor is found in U.S. Pat. No. 3,912,328 to A. Tanaka.
However, many adult passengers find the degree of restraint associated with the automatic-locking mode uncomfortable and prefer a retractor mechanism which permits a relatively unrestrained movement within the vehicle during non-emergency conditions. To provide this alternative mode, it is known in the art to make retractor mechanisms acceleration-sensitive ("ELR"), i.e., means are provided within the retractor for sensing accelerative forces acting upon the vehicle and/or safety belt and for detecting acceleration levels of a predetermined value and for locking the retractor against further extractive movement of the belt upon detection thereof.
An example of vehicle inertia sensor operating in conjunction with a retractor mechanism is discussed in U.S. Pat. No. 4,018,400 to C. Henderson, and an example of a retractor having an actuator which releases a spring-biased pawl to lock the retractor reel in response to belt accelerations is disclosed in U.S. Pat. No. 3,604,655 to D. Jones.
In operation, these ELR-type of retractor mechanisms provide the advantage of a relatively unfettered degree of movement of the adult passenger within the vehicle during normal conditions, and lock up to restrain the passenger against further extractive movement of the belt only upon occurrence of the emergency condition. However, their disadvantage is that they are not suitable for restraining small children or infant seats or carriers within the vehicles during emergency or nonemergency conditions, for reasons discussed below.
It is not uncommon to find retractors capable of operating selectively in either an ALR or ELR mode, or both. R. Fisher, in U.S. Pat. No. 4,042,277, discloses a restraint system having floor and pillar mounted retractors, one of which locks electrically into the ALR mode upon buckling-up. A similar, free pull retractor which locks electromagnetically upon buckling-up is shown in U.S. Pat. No. 3,890,003 to A. Close. A manually-actuated cinch lock operating independently of associated comfort mechanisms, e.g., the ELR mode, is disclosed in U.S. Pat. No. 4,427,164 to Rumpf. In U.S. Pat. No. 4,428,545 to K. Naitoh, a manual locking mechanism is provided which is operable either electrically or mechanically. Combination ELR and ALR retractors which are converted to the ALR mode upon full extraction of the belt from the retractor are disclosed in U.S. Pat. No. 4,518,132 to T. Schmidt and U.S. Pat. No. 4,552,319 to Gavagan, et al.
In smaller vehicles, particularly compact-sized cars, it is not unusual to find a passenger restraint system in which a knee bolster is used to restrain the knees, and hence lower torso, of a passenger in a seat against forward movement during emergency conditions, which is supplemented by a chest belt having one end wound onto an acceleration-sensitive retractor attached at the lower, inward side of the seat and passing across the chest of the passenger to engage with quick-release means attached to the adjacent door or door frame, usually by means of a tongue-plate and quick-release buckle arrangement. Such restraint systems have the advantage of safely restraining adult pssengers during emergency conditions while permitting relatively unrestrained movement with the vehicle during normal operation.
However, these latter systems present a problem when used to restrain infants or small children. Typical state laws require children under a certain weight or age limit to be primarily seated within a safety seat or carrier which is, in turn, safely restrained within the vehicle's seat. For children over the limit in age or size, the law merely requires that they be adequately restrained by a safety belt arrangement. However, the knee bolster and acceleration-sensitive chest belt are inadequate for restraining either an infant seat or a small child, inasmuch as the child's leg length is typically too short for the knee bolster to function correctly and the chest belt typically will pass too high on the child to safely restrain the child's upper torso. Additionally, acceleration-sensitive retractors are undesirable for restraining small children or infant seats within the vehicle during normal operation for the reasons discussed above.
It is therefore an object of the present invention to provide a dual mode passenger restraint system for a vehicle which is capable of operating in either an acceleration-sensitive chest belt mode in conjunction with a knee bolster, or in an automatic-locking lap belt or safety-seat-restraining mode independently of the bolster.
It is a further object of the present invention to provide a kit for retrofitting a vehicle already equipped with a knee bolster and an acceleration-sensitive chest belt with such a dual mode system.